Apparatus for dressing a grinding wheel to a predetermined configuration



April 11, 1950 c. WILSON 2,503,646 APPARATUS FOR DRESSING A GRINDINGWHEEL, 7 TO A PREDETERMINED CONFIGURATION Filed Feb. 25, 1946 5Sheets-Sheet 1 A j 45 i 6o INVENTDR JOHN C. WIL$OM .61 r: 5 f" g I Amman5 Sheets$heet 2 [rllvv GRINDING WHEEL NFIGURATION a /w i-MW ILSON NG A APREDETERMINED CO April 11, 1950 Filed Feb. 23, 1946 April 11, 1950 J. c.WILSON 2,503 646 APPARATUS FOR DRESSING A GRINDING WHEEL TO APREDETERMINED CONFIGURATION Filed Feb. 23, 1946 5 Sheets-Sheet 3 I I I II I Invmron JOHN C. WILSON,

April 11, 1950 J. c. WILSON 2,503,646

APPARATUS FOR DRESSING A GRINDING WHEEL TO A PREDETERMINED CONFIGURATION5 Sheets-Sheet 4 INVENTOR JOHN C. WILJON,

Filed Feb. 25, 1946 Arronun;

April 11, 1 950 J. c. WILSON 2,503,646 APPARATUS FOR RESSING A GRINDINGWHEEL I TO A PREDETERMINED CONFIGURATION Filed Feb. 23, 1946 5Sheets-Sheet 5 Y I77 I/// I36 I20 NEU'TRM \RAPIDREVEKSE I H5 H6 5h 110 11/4 RAPID APFROACH I Q 2 I ur a L 5 JOHN c. WISBN Arronnzvs PatentedApr. 11, 1950 UNITED STATES PATENT OFFICE APPARATUS FOR DRESSING AGRINDING WHEEL TO A PREDETERMINED CON- 1 FIGURATION a corporation ofOhio Application February 23, 194 Serial No. 649,466 J I l Thisinvention relates to grinding ,machines,

and particularly' to an apparatus for dressing a grinding wheel to apredetermined configuration.

Th particular'object of this invention is to provide an; improvedmechanism for exactly shaping a grinding wheel for the production ofprecision workpieces. In the shaping of workpieces by grinding, it isnecessary that the wheel be exactly shaped and that it be dressed moreor less often in order to restor its configuration after it has beenused for grinding. Heretofore, the shaping of a grinding wheel to anyparticular configuration has involved a considerable amount of apparatuswhich was expensive and, at best,- only approximately accurate.

The present invention contemplates the use of a template and a dressingtoolwith servomotor means actuated by a follower for controlling thesupply of power to motor means that drive the dressing tool.

{By providing a template and a follower therefor and driving aservomotor mechanism or detecting means by the follower, a very accuratetracin of the template is possible. Then, through suitable amplifyingequipment, the servomotor or detecting means releases power to motormeans that drive the dressing tool in a path which corresponds exactlywith that of the template follower.

Accordingly, another object of the present invention is to provide agrinding wheel dressing mechanism in which ther is a dressing toolthatis controlled by a template and template follower throughsuitablepower amplifying means.

Another object is to provide a dressing mechanism having a diamondtracer or the like which is controlled by a template and followerthroughamplifying means, and in which the dressing tool can trace-substantiallyany predetermined con- 9 n: he.w s i A I -..'-Ihe foregoing object isaccomplished by traversing the wheel with the dressing tool at apredetermined rate and varying the said rate in accordance with theradial movements of the'dresslng tool toward and from the wheel Thispermits steep cuts to be made on the wheel while maintainingsubstantially a constant feeding;

c t n 9 1 1 Still another object of ;-the present invention is;-to-provide an automatic dressing means for a grinding wheel in which therate of dressingmay be adj usted toaccommodatethe device; to theparticular; type ;and size of wheel;- and to the exit ihe-c et u izwh ohisv be n formed.v h -,3

5 clai s. (01. -11) It is still another object to provide a grindingwheel dressing mechanism which includes. template and which may beadapted for tracing; any contour on a wheel merely by replacing thetemplate.

A further object is the provision of a unitary dressing mechanism for agrinding wheel which is adapted for being .mounted on a grinding machinetable or on agrinding machine bed and which requires no modification ofthe grinding machine structure when used in connection;

therewith. I v v These and other objects and advantages will-f becomemore apparent upon reference to the following descriptionandaccompanying draw-- ings in which:

Figure l is "a perspective View of a typical grinding machine having adressing mechanism according to this invention mounted on thebedthereof; T

Figure 2 is a view looking longitudinally of the bed toward the wheelsubstantially as'indicated by the arrow 2 on Figure 1 and showing thewheel and wheel dressing mechanism;

Figure 3 is a plan view taken over the whee1' Figure 7 is a plan Viewover a grindingmachine:

showing a dressingmechanism according to this. invention secured to thegrinder bed rather than the grinder table.

in Figures 1, 2 and 3 a grinding machine having a bed. in upon which isreciprocably mounted a workpiece supporting table l2, Adjacent to orattached to .the' bed in is a column 14 which mounts (a saddle l6,,forvertical reciprocation. The"',sadd1e""l6 iin turn'supports awheel'jiiead, structure" ['8 tier. lateral/reciprocation, the. saidwheel head structure including a drivemotor and 'the grinding. wheelmounted according'to-w'elli known practices;

.The saddle l6 lanai-mer er; mew e'ei head It and wheel may-be adjustedvertically n mm se era .l a u f i.

- the nine:

"Referring to the drawings; there"isiillustrated';

nism indicated at 24 or by any suitable power driven or automatic means.The table I2 is also preferably reciprocated by power means to traversethe wheel and workpiece relatively.

Also mounted on the bed is a dressing unit generally indicated at andconsisting of a housing 28 which reciprocably mounts'a first slide 30which is connected with the plunger 32 of a motor 34 carried in or onthe said housing 28. The slide 30 in turn supports a mechanism suitablefor guiding a second slide 36 that is con nected with the plunger of amotor 4!? supported on the said mechanism or on the said first slide.

The second slide has mounted thereon a rod 42 that supports a dressingpoint 44 which is preferably diamond tipped. Also carried on the slide"36 is a tracer mechanism 46, better illustrated in Figure 5, thatincludes a rod 48 carrying the tracer point 50. The rod Mi is pivotallymounted at 52 in the housing 54 of the tracer unit and is continuouslyurged about the pivot by a spring 56 to maintain the follower againstthe template. The template, indicated at 58, is stationarily supportedon a part of the housing 28 or some other suitable stationary member.

The rod 48 carries at its inner end a pair of smooth plates I50 whichlie between a pair of nozzles 62 and 64. The nozzles, or orifices,discharge a fluid such as air into the space between the said nozzlesand the plates 80 at a predetermined rate. Then, as the rod 43 is movedabout its pivot due to the action of the template on the tracer point,the volume of fluid dissuitable control mechanisms, actuates the motors34 and 40 to drive the dressing tool in a path corresponding to the pathof the template.

The circuit for accomplishing this is more fully shown in Figure 6wherein it will be seen that the jet 62 is connected by a conduit 66 toan expansible bellows 0B. The conduit 66 is also connected by a conduitI0 through an orifice I2 of aconduit 14 that leads to a substantiallyconstant ressure fluid source 16. The jet 64 is similarly connected by aconduit 78 with a bellows 80 and the conduit I8 is connected by aconduit 82 through the orifice 84 with the conduit The bellows 68 isanchored at its conduit end and has connected at its other end the valvemember 86. The control valve 83 has its service ports 90 and 92connected with opposite sides of the plunger 38 of the motor 40. Thevalve 88 also comprises the exhaust connections 94 and the inlet port 96is connected by a conduit 98 through an adjustable choke valve 100 withthe discharge side of a pump I02 that may draw fluid from a reservoirI534.

The bellows 68 is fitted with adjustable springs I06 by means of whichit may be adjusted exactly to center the valve member 86 under normaloperating conditions. When the valve, member 83 is exactly centered, theinlet and exhaust ports are exactly sealed off and any movement of thevalve member in either direction will effect fluid com- "munication ofone side of motor 40 with the inlet 1 and of the other side thereofwithexhaust so that immediate movement of the said motor occurs when thesaid valve member is displaced from the position shown in the drawings.

The bellows 80 is similarly anchored at its conduit end and has itsopposite end connected with the valve rod of the valve member I08 01' avalve I10. The valve I I0 has an inlet port or orifice at H2 thatcommunicates with the space H4 and a conduit I16 communicates this spacewith a second space II8 through a port or orifice I20. The space IIB isin turn connected with exhaust through a conduit I22. The arrangement issuch that movement of the valve member I08 in either direction from theposition shown in the drawing effects a restriction of the passagethrough the valve for a purpose which will become more apparenthereinafter. The bellows is fitted with adjusting mechanism as at I24for the purpose of effecting an initial setting thereof under anypredetermined conditions.

The motor 34 within which is reciprocable the plunger 32 has itsopposite ends connected to the service ports I24 and I26 of a valve I28.The said valve also has an inlet port I 30 connected with the dischargeside of the pump I02, and an exhaust port I32 connected directly withthe reservoir I04 and a second exhaust port I34 connected through anadjustable choke valve I35 with the inlet port II2 of the valve IIO. Athird exhaust port at I38 is also connected directlywith the reservoirI04.

The valve I28 includes a valve member [40 which is movable into aplurality of positions by the lever I42 as indicated by the dot-dashlines and legends on the drawing. When the lever I42 is shifteddownwardly into its Rapid Approach" position the valve member I40 isshifted upwardly to connect the ports I26 and I30 and the ports I24 andI38. This supplies fluid to the left side of the plunger 32 while freelyexhausting the right side thereof and brings about the rapid approach ofthe dressing tool to the grinding wheel.

When the dressing tool is near the wheel the lever I42 is shifted to itsFeed" position, which will be explained more fully hereinafter, thisposition of the valve member I40 produces a controlled travel of theplunger 32.

When the lever I42 is moved into its "Neutral" position the supply offluid to the motor 34 is interrupted and the said motor halts. The motor34 may be reversed and the plunger 32 retracted rapidly by shifting thelever I42 into the position marked Rapid Reverse. With the valve memberin its last mentioned position, pressure fluidis supplied to the rightend of the motor 34 while the left end thereof is freely exhausted tothe reservoir.

In operation, assuming that the dressing tool has been brought to aposition adjacent the grind ing wheel and that the lever I42 has beenshifted into its feed position, the dressing tool continues to approachthe wheel at a rate which is determined by the setting of the chokevalve I 36 in'the exhaust line of the motor 34. When the templatefollower 50 meets the first incline on the template 58, the arm 48 isrocked about its pivot point 52 in a counter-clockwise direction asviewed in the This movement of the arm 48 moves drawings. the plates 60relative to the orifices 62 and 64 to decrease the flow from the formeror permittinga greater flow from the latter.

With the flow through the orifice B2 reduced,

the pressure drop acr'ossthe orifice I2 is reduced and a greaterpressure stands in the conduits I0 j and 66, and therefore, in thebellows 68. Thetracing mechanism 45- and the dressing tool: 44.,

The dressing tool thus describes an incline on the grinding .wheel inexact conformitywith the incline on the template.

'. Simultaneously,l the flow through xthel orifice 64' is modified sothat there is agreateifpressure drop across the orifice 64 and areduced-pressure.

stands in the conduit '82 and 18 andidthf belt-"z lowst80. The reductioninpressurerams bel-.

lows 80 permits it to retract andshiftivalv'e mem ber. I08 to increasethe restriction to the fiow of:- fluid'through the valve H0; Thiseffects 1 a" re'-" duction in speed of the plunger 32 andg the slide 30connected therewith. It will be apparent that the speed of the crosstravel or traverse of the dressing tool is generally inverselyproportional to the rate of its in and out feeding motions because ofthe associated jets 62 and E4 and that,-

by selecting a suitable valve at I I0 and a suitable bellows at 80, anycontour however complex could be accurately generated on the peripheryof a grinding wheel. i

- Inorder to control the cross travel or traverse rate of the dressingtool 44, the valve I36 is provided which is adjustable by means of ahand wheel Ga-positioned to be available to thema chine .operator.Likewise, thein and out feed rate of the dressing tool may be'controlledby adjustment of the knob l00a of the valve I00, this knoblikewise being positioned for the convenience of the operator.

While any dressing tool sufliciently hard to cut a grinding wheel may beemployed, I prefer a diamond tipped tool which is formed to a radius ofbetween 0.010" and 0.020". It has been found that a dressing tool soshaped has substantially longer life than one with a fine point thereonor having a flat edge. A pointed or straight edged tool tends to wearinto a shape which is substantially the same as that to which thedressin tool according to this invention is shaped. Accordingly, adressing tool formed to the radius indicated has a tendency to maintainits original shape throughout its working life.

In Figure '7 there is illustrated a somewhat modified arrangementwherein the dressing mechanism 200 is attached to the rear surface ofthe bed 202 and has its cross travel Side 204 extended to lie over thegrinder tablev 206. The vertically reciprocable slide 208 carries thetracer mechanism 2 I 0 that follows the template 2 I 2, the latter beingstationarily mounted on the dressing mechanism or grinder bed. The slide208 also carries the arm 2 I4 within which is mounted the dressing tool2 l6 which cutsthe wheel 2| 8.

While in the form illustrated in Figure 1, the table l2 may bereciprocated to bring the dressing tool 44 directly under the wheel 20,.in Figure 7 the dressing mechanism must beso. located on the bed andthe arm 2 I4 must be soproportioned that the tool 2 I6 is in alignmentwith the vertical center line of the wheel. Then, when the dressingattachment is idle, the slide 204 .is retracted to carry the mechanismback from the wheel so that the workpiece being operated may bereamrocated thereunder.

It will be understood that this invention is susceptible to modificationin order' to' adopt it to different usages and -cor'1ditions','andaccordingly; i' it ls -desired to comprehend such modificationswithin'this invention as ma fall within thescope of the appended claims.I claim:

' 1. In a dressing device for dressing agrinding wheel, the combinationof: a dressing tool; a pair of superposed slides supporting said toolfor move-. ment in two angularly related directions; first and secondmotor means respectively connected with said slides for actuating saidtool in different di-. rectioris in a common plane; a, stationary tem--plate; a follower movably connected with said tool to be movabletherewith for following said template;- means :for controlling thesupply of actuating energy to said motors so the supply to one";increasesasthe supply to the other decreasesir and controlling meanscontrolled by the actuation: of said follower b said'template inmovements: relative to said toolfor controlling said last men+fi tionedmeans, said controlling means including opposed jets rigid relative tosaid tool, and a baiile betweenxsaidrjets connected; to move with saidfollower, one of said jets being constructed and adapted to'vcontrolsaid first motor means and the other thereof being-constructed andadapted to control said second motor means.

2. A device for dressing a grinding wheel comprisingyabed; a first slideon said bed; a secondslide carried on said first slide; first andsecond: motor means for actuating said first and second slidesrespectively; a'template stationary relative to said-bed and a followertherefor movably car-- ried by said second slide; means controlled bymovement of said follower relative to said second slide for controllingthe actuation of said motor 1.

means for maintaining a predetermined relative position between saidfollower and said second slide; a dressing tool carried on said secondslide adapted for shaping a grinding wheel; and controlling meanscontrolled by the actuation of said follower by said template inmovements relative to said tool for controlling said last mentionedmeans, said controlling means including opposed jets rigid relative tosaid tool, and a baflle between said jets connected to move with saidfollower, one of said jets being constructed and adapted to control saidfirst motor means and the other thereof being constructed and adapted tocontrol said second motor means.

3. In a grinding machine having a grinding wheel and a bed, a dressingdevice for dressing said grinding wheel comprising; a bed adapted forbeing mounted on the bed of said grinding machine; superposed slidescarried on the dresser bed and individual motor means connected to saidslides; a dressing tool and a template follower movably carried on oneof said slides and a template which said follower follows mountedstationarily relative to said dresser bed; fluid operable means forcontrolling the actuation of said motor means to maintain said followeragainst said template, and said follower and said one of said slides ina predetermined relative position in one direction, whereby saiddressing tool describes a path of the same shape as said template, saidfluid operable means including: a plurality of opposed Jets rigid withsaidone slide; a baflle member between said jets connected rigidly tosaid follower; conduit means connecting each jet independently to asource. of fluid; an expansible member in the circuit of each jet; avalve including a movable valve member connected to said expansiblemember of ea'ch'circuit for actuation; a fluid connection from eachvalve to each slide actuating motor; and a fluid connection controllingthe supply of actuating energy to said motors whereby the supply to oneincreases as the supply to the other decreases.

4. In combination in a grinding wheel dresser; a dressing tool:superposed slides supporting said tool; first and second fluid operablemotor means connected with said slides for actuating the same and .saidtool in directions axial and radial of the wheel; a fluid source forsupplying said motor means; a variable restricting valve adapted forserial connection with said first motor means; a control valveconnecting said source with said first motor means and movable into .afirst position-to drive said first motor means at a rapid rate in onedirection or, into a second position to drive'said first motor means ina rapid rate in the opposite direction or, into a third position toconnect said iiuid source and said restricting valve serially with saidfirst motor means; valve means controlling the supply of fluid tosaidsecond motor means for actuating it in opposite directions; a stationarytemplate and a follower carried with said tool; fluid pressureresponsive means connected with said restricting valve and with saidlast mentioned valve means for controlling the actuation of said firstand second motor means; jets discharging to the atmosphere andhydraulically connected with said fluid pressure responsive means; meansfor supplying fluid at a substantially constant rate to said jets fordischarge to the atmosphere therefrom; and a baflie actuated by saidtemplate follower and positioned to influence said jets oppositely.

5. In a grinding wheel dressing device for sha ing grinding wheels, thecombination of; superposed slides; :a; diamond pointed dressing toolmounted on one slide; first and second fluid op-- fluid pressureresponsive means connected to eachv of said'jets to be varied by thevariation in pressure at said jet means, valve means connected toeach ofsaid fluid pressure responsive means for. controlling the direction andrate of fluid flow to each of said motor means, and means for supply--.

ing fluid to said jets for discharge therefrom JOHN 0. WILSON.

REFERENCES ClLTED The following references are of record in th file ofthis patent: 1

UNITED STATES PATENTS Number Name Date 1,960,760 Sutton May 29, 19342,025,748 Howe H--. Dec. 31, 1935 $2,226,677 Nikhman Dec. 31, 19402,259,472 Johnson Oct. 21, 1941 2,335,305 Parsons Nov. 30, 19432,434,853 Johnson Jan. 20, 1948 2,447,478 vRundt- Aug. 17, 1948'2,469,255

Barnes May 3, 1949--

